An iron-silicon-aluminum alloy known as Sendust is available commercially and is formed by a fusion casting process. A magnetic head assembly utilizing pole tips of such material is disclosed in Robert A. Schneider U.S. Pat. No. 3,417,386 issued Dec. 17, 1968. The casting process used in forming this material generates voids within the ingot due to shrinkage; also the limited cooling rate is responsible for grain enlargement. In addition the differences in the cooling rate within the volume of the cast ingot produces large variation in grain size.
Prior workers have experimented with the sintering of iron-silicon-aluminum alloys, as evidenced by the disclosures of U.S. Pat. No. 2,988,806, issued June 20, 1961, and U.S. Pat. No. 2,992,474, issued July 18, 1961. A serious drawback of such sintered material for magnetic recording heads, however, is its high degree of porosity. Furthermore, both the cast alloy material and the sintered material found in the prior art exhibit a lack of cohesion between the grains, which is observed as a lesser degree of physical hardness than would be optimum for the tape contacting surface of a magnetic head assembly.